Leaf-spring.



E. G. DANN.

LEAF SPRING.

APPLICATION FILED weal. m4.

Patented Apr. 3, 1917.

CompressgalAir.

1 I? ll LEAF-SPRING.

1,22L695, Specification of Letters Patent. Patented Apr. 3 191?.

Application filed August 31, 1914. Serial No. 859,472.

To all whom it may concern.-

Be it known that I, ERNEST G. DANN, a citizen of the United States,residing at Chicago, in the county of Cook and State 5 of Illinois, haveinvented certain new and useful Improvements in Leaf-Springs, of whichthe following is a specification. 5

My invention relates to leaf springs, either elliptical orsemi-elliptical, such, for example, as are commonly employed forsupporting vehicle bodies on their running gear, and the object of theinvention is to increase the durability of such springs, and to insure ahigh degree .of resiliency, by preventing the corrosion of the bearingsurfaces of the superposed leaves.

r In a compound leaf spring it is, of course, intended that thesuperposed leaves should have a certain amount of relative movement 2one upon the other, and such movement is, in fact, essential if thespring is to have any, considerable degree of resiliency. The relativemovement between the leaves'is much hindered by the corrosion of thebearing surfaces due to moisture. Water is likely to work in between theleaves of a spring. Even the moisture of the air will bring about acertain amount of corrosion. Any roughening of the surfaces in contact,whether from this cause or another, by checking the freedom of movementof one leaf upon the other detracts from the resiliency of the spring asa whole. It has been. customary, in order to overcome the stiffness ofcompound leaf springs and add to their life, to occas ionally take thesprings apart and lubricate their bearing surfaces. This is an expedientwhich is obviously only temporarily effective. The lubricant soon worksout under the continual pressure and movement of one leaf upon theother. Another expedient is to insert lubricant carrier strips betweenthe leaves of a spring.

My present invention contemplates a different method of procedure foraccomplishing the same result with more permanent effect at considerablyless expense. The invention provides for covering the bearing surfacesof the leaves of a steel compound leaf spring with a non-corrosiblemetallic film or facing which is permanently united with the steel ofthe spring by being in part incorporated in .the superficial portions ofthe leaves. The metal used is preferably of a soft amorphous character,such as lead, bronze, white metal, or alloys of these or similar metals,so that the bearing surfaces provided are not only unaffected by theweather but are smoother and develop less friction than would steelsurfaces even if no corrosion took place. The facings have, in effect, alubricating function, the distinction being that while the ordinarylubricant, if applied to the leaves of a compound spring, Will soon Workout leaving the steel exposed to corrosion, the lubricating'faces of myinvention form structurally a part of the steel and will be relativelypermanent That is, they will last until actually worn away by attrition.The provision of the springs with these non-corrosible lubricatingfacesbesides increasing the resiliency of the springs adds to their life assprings are necessarily weakened by the corrosion of the leaves.-Moreover, a stiff spring is much more likely to break than one which isresilient.

The invention'is illustrated in a diagrammatic way in the accompanyingdrawing in which Figure 1 is a view, in perspective, of asemi-elliptical compound spring of the sort suitable for being treatedas provided by my invention.

Fig. 2 is a View, illustrating a preferred method of applying thefacings to the springs, and

Fig. 3 is an edge view of one of the leaves of the spring showing thefacing applied thereto.

Like characters of reference desi nate like parts in the several figuresof the rawings.

In carrying out the invention the upper surface of the master leaf A isprovided with a non-corrosive lubricating facing B preferably a triflelonger thanthe superposed leaf C. The portion of the upper surface ofthe leaf O, on which leaf D bears, is similarly treated. The undersurface of C is also preferably provided with the facing ofmy invention.This is desirable but not essential as it will be possible to obtainsome of the advantages of my invention by treating only one of each pairof contacting faces.

The other leaves D, E, F and G are provided with facings of the samecharacter. These facings are preferably produced in the mannerdiagrammatically shown in Fig. 2. H represents a strip or wire of themetal tobe used for making the facing, lead,

being treated. The facing metal, in fact,

penetrates to a certain distance into the structure of the steel. Theoperation is very different from one of plating. The ordinary platingmethods will not produce a covering for the leaves which willbe-permanent. A plating will very soon crack off with the constantvibration, attrition and flexure of the leaves. It is the integral,structurally unified relation between the facing and the steel of thespring which is produced when the facing is made as above described,which gives said facing its utility for the purpose intended.

I claim:

1. A compound leaf spring composed of superposed leaves having theirsurfaces of contact one with another provided with facings ofnon-corrosive metal integrally united with the metal composing theleaves.

2. A compound leaf spring composed of superposed leaves having theirsurfaces of contact one with another provided with facings ofnon-corrosive metal integrally united with the metal composing theleaves by being forced against the leaves while in molten condition.

3. A compound leaf spring composed of superposed steel leaves havingtheir surfaces of contact one with another provided with facings of ametal softer than steel and of a lubricating character integrally unitedwith the steel composing the leaves.

4. A compound leaf spring composed of superposed steel leaves havingtheir surfaces of contact provided with integral facings ofnon-corrosive metal of a lubricating character.

5. A laminated structure comprising laminae of yieldable material and asurface of lubricating material interposed between each contacting pairof laminae and integrally united with one of them.

6. A laminated structure comprising laminae of yieldable material and asurface of lubricating material interposed between each contacting pairof laminae and inseparably united with one of-them.

7. A laminated structure comprising laminae of yieldable material and asurface of lubricating material interposed between each contacting pairof laminae and inseparably united with one of them by adhesion only.

ERNEST G. DANN.

Witnesses:

L. A. FALKENBERG,

R. KUEHN.

